(a) Field of the Invention
The present invention relates to a method and an apparatus for cancellation of a transient voltage spike. More particularly, the present invention relates to a method and an apparatus for cancellation of a transient voltage spike occurring in a single photon detector.
(b) Description of the Related Art
In a quantum cryptography communication system, a receiver may detect a single photon using an avalanche photodiode.
Since an intensity of light corresponding to a single photon level is applied in the receiver, it is difficult for the receiver to detect an optical signal using the avalanche photodiode. Accordingly, the receiver may operate the avalanche photodiode in a gated Geiger mode and detect an optical signal corresponding to a single photon. Here, when a voltage pulse is applied to an inverse-bias of the avalanche photodiode around a breakdown voltage, it is possible to obtain an infinite instant gain.
On the other hand, when a gating pulse and a direct current (DC) voltage corresponding to a breakdown voltage are applied to a negative electrode of the avalanche photodiode, a voltage signal component may be combined with a positive electrode due to a parasitic capacitance component of the avalanche photodiode.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.